bug#56210: 29.0.50; Keyboard macros do not trigger after-change-functions

[Richard Hansen]

On 2022-06-27 12:54, Eli Zaretskii wrote:
> > I changed the test to switch to the temporary buffer in the 
> > selected window and it now reliably inserts "x" into the temporary 
> > buffer.  It still doesn't run the `after-change-functions' hook, 
> > however.  Updated test code:
> >
> > ;; -*- lexical-binding: t; -*-
> > (require 'ert)
> > (require 'ert-x)
> > (defvar-local acf 0)
> > (defun acf (&rest _) (setq-local acf (1+ acf)))
> > (ert-deftest test ()
> >     (ert-with-test-buffer ()
> >       (let ((b (current-buffer)))
> >         (save-window-excursion
> >           (with-current-buffer-window b
> >               `(display-buffer-below-selected
> >                 (body-function
> >                  . ,(lambda (window)
> >                       (select-window window t)
> >                       (should (eq (current-buffer) b))
> >                       (setq-local acf 0)
> >                       ;; Note that LOCAL is t:
> >                       (add-hook 'after-change-functions #'acf nil t)
> >                       (should (memq #'acf after-change-functions))
> >                       (execute-kbd-macro (kbd "x"))
> >                       (should (equal (buffer-string) "x"))
> >                       ;; The above checks pass, this check fails:
> >                       (should (equal acf 1)))))
> >               nil)))))
>
> Your test calls with-current-buffer-window, which calls 
> temp-buffer-window-setup, which inhibits modification hooks:

I looked into this a bit more.  It turns out that `inhibit-modification-hooks' 
is actually nil in the body of `with-current-buffer-window', as expected.  It 
is t in the above test code because of `display-buffer-below-selected', which 
calls `window--display-buffer', which does the following:

    (when (functionp (cdr (assq 'body-function alist)))
      (let ((inhibit-read-only t)
            (inhibit-modification-hooks t))
        (funcall (cdr (assq 'body-function alist)) window)))

The `body-function' action alist entry was added in Emacs 28.1 by commit 
3273e2ace78 [1] for bug#39822 [2].  Presumably the modification hooks are 
inhibited during the execution of `body-function' because `body-function' was 
added to replace the (now-deprecated) `with-displayed-buffer-window' macro, 
which inhibits them.  The `with-displayed-buffer-window' macro has inhibited 
them ever since the macro was first added to Emacs 25.1 by commit f0f70ec0bc5 
[3] for bug#17809 [4].

I'm guessing that `body-function' is only intended for initial buffer set-up, 
thus modification hooks are inhibited.  However, the body of 
`with-current-buffer-window' is also only intended for initial buffer set-up 
(it actually runs before `body-function' and before the buffer is displayed), 
so the inconsistency is unexpected and awkward.  Either both should inhibit the 
modification hooks, or neither should.


[1] 
https://git.savannah.gnu.org/cgit/emacs.git/commit/?id=3273e2ace788a58bef77cef936021d151815ea94
[2] https://debbugs.gnu.org/cgi/bugreport.cgi?bug=39822
[3] 
https://git.savannah.gnu.org/cgit/emacs.git/commit/?id=f0f70ec0bc55e452ea29b5cf3f532740966b0192
[4] https://debbugs.gnu.org/cgi/bugreport.cgi?bug=17809

OpenPGP_signature
Description: OpenPGP digital signature